ELIZABETH CITY CSO GREEN INFRASTRUCTURE PROJECT

The City of Elizabeth recently completed a Combined Sewer Overflow (CSO) Project that is being funded with approximately $6 million in loans from the NJ Water Bank, a joint low-rate funding program of the DEP and the NJ I-Bank. This project qualified for principal forgiveness totaling $1,674,985 as it improved conditions for combined sewer overflows. Including interest cost savings, total savings for this project is estimated to be $3,550,965 over the 30-year term of the loan or 56% of the total project cost. In addition, this project created an estimated 74 direct construction jobs. 

The City of Elizabeth is one of the 21 municipalities in New Jersey with a combined sewer system (CSS). Under optimal conditions, the stormwater and sewage are combined and conveyed to a sewage treatment plant. But when the system is overwhelmed by extra volume from excessive rain events, it diverts all flows (stormwater AND sewage) into nearby waterways, and sometimes backs it up into neighborhoods, threatening human health and the environment. CSSs are expensive and complicated problems to address because they connect to each other from one municipality to another.

In order to address the CSO issue, Elizabeth City installed additional inlets at the intersection of Trumbull and Sixth Street several feet off the curb allowing the existing drainage system to function during smaller storms. When the capacity of the existing catch basins is exceeded, excess stormwater is piped to a watertight 1-million-gallon concrete vault to store the flow. The entire structure is wrapped in an impermeable pond liner beneath the property acquired for this project and equipped with a pump station. Sensors installed in the combined sewer system activate the pumps after wet weather events triggering the tank to convey the discharge into the sewer system when it has sufficient conveyance capacity for treatment at the Joint Meeting of Essex and Union Counties Wastewater Treatment Plant. 

A rain garden was also installed as a test case for green infrastructure as well as the creation of a plaza for the enjoyment of City residents. By addressing issues with the CSS, the City was able to limit roadway flooding and maintain passable travel lanes.

According to J. Christian Bollwage, Mayor of Elizabeth City, "This project is an example of our commitment to improve our infrastructure strategically and improve the quality of life for our residents. We have provided CSO Abatement, improved traffic flow and created recreational space all financed with low-interest rates and principal forgiveness, saving our ratepayers money over time."

The project was designed by Mott MacDonald, headquartered in Iselin, NJ and constructed by PM Construction Corporation, based out of Hillside, NJ.